Help with battery system design

I have been in contact and received a quote for a grid tied battery back up system but it was not designed as what I am hoping for. My goal was to have a battery backup system that would be in use all the time probably through and separate loads panel. If the solar panels were not satisfying the load requirement to keep the batteries fully charged, then I wanted to use the grid for that purpose. (also have a 22kva propane back up generator).
I really don't want to invest so much into a battery backup system and have the batteries just sit there not being used only in a grid down situation. I'm not really looking to back feed and excess power back into the grid but that is an option. I am ok with a manual transfer switch if necessary
The company is telling me that is not doable. Isn't that how a solar generator works?
Any help is most appreciated

If you are on Time of Use billing with the utility, the system as you described is possible and would be called a Self Consumption system where an inverter feeds a Critical Load Subpanel. Such a system would charge the batteries with solar panels and excess could be used to offset utility usage and/or feed back to the grid, NET metering. Between 4 to 9pm when rates go up, the system could be programmed to stop using utility power and draw only from the batteries.
Some Inverters have 2 AC inputs so you could have the grid connected to AC1 and a generator connected to AC2. The inverter takes care of all the switching and can even auto start the gen if necessary.
If you are not on ToU billing then having batteries is a convenience in the event of an outage but that doesn't necessarily mean you have to cycle the batteries just because they are there. Batteries will experience age degradation even if not used so light cycling makes sense to partially offset utility usage but heavier cycling will cause the cells to loose capacity faster.

What you want is doable, but not optimal. You should use the batteries to accomplish something, not for the sake of using them.

If you have grid power, and net metering, then let the grid deal with excess power. You could have self consumption, but then you have about 5-10% conversion loss (pv-battery-load), and battery wear.

If you have something like Connected Solutions which has the utility pay you for the right to use your battery during peak times, that is beneficial.

The system you asked for is basically an off grid system with grid and generator as backup.

so using the battery backup on a regular basis is not recommended for a grid tied system? only to have them there in the event that the grid is down?

DIYrich said:

What you want is doable, but not optimal. You should use the batteries to accomplish something, not for the sake of using them.

If you have grid power, and net metering, then let the grid deal with excess power. You could have self consumption, but then you have about 5-10% conversion loss (pv-battery-load), and battery wear.

If you have something like Connected Solutions which has the utility pay you for the right to use your battery during peak times, that is beneficial.

The system you asked for is basically an off grid system with grid and generator as backup.

Click to expand...

I'm not familiar with the term "connected solutions" what does that mean?